This invention relates to an improved method and apparatus for automatically separating and processing supple sheets from several stacks in a single operation whereby use is made of separating elements, more particularly pick-up heads, as illustrated in Belgian Pat. No. 816,940 or U.S. Pat. No. 3,981,495, the latter patent being expressly incorporated by reference.
Said Belgian patent describes a universal automatic apparatus for separating supple sheets from stacks, which apparatus is made of a rigid frame comprising adjustable transverse rods to which universal separating elements with special pick-up heads are adjustably attached, and whereby the pick-up heads are disposed with a suitable orientation over the corners or edges of the stacks. The separating process with this universal apparatus is as follows:
The stack is compressed by means of the separating elements in the civinity of a pair of opposite upper edges of the stack. In order to pick up the sheet, sharp projections engage the sheet near its edges. These projections are fixed to the underside of a pricking element that is rotatably mounted in the pickup head. Subsequently, the projections are laterally moved apart over a sufficient distance, whereby the engaged sheet is tightened and whereby finally the separating elements with the engaged and tightened sheet are moved away from the stack. Means are also provided to synchronize the up-and-down movement and the application of pressure on the stack by the pick-up heads, as well as the picking and tightening movements of the picking devices that are rotatably bearing-mounted in the pick-up heads.
Furthermore, on page 11 of the Belgian Pat. No. 816,940 of Applicant, it is also suggested to mount one or more of such separating apparatus over an intermittently progressing conveyer belt, so that in a suitable manner several stacks can be formed and/or removed sheet by sheet. It is also described in FIGS. 16 to 18 of the Belgian Pat. No. 806,540 that with the same separating elements it is possible to successively pick up one sheet from a first stack, next to deposit this sheet onto a second stack, and finally to pick up at least two sheets from this second stack by means of needles with a suitable projecting length.
Both processes however have two important disadvantages. The whole process involves a sequence of movements of the separating elements and the stacks which is complicated, extensive, inconvenient to operate, slow, unstable and consequently hard to control accurately. Another disadvantage is a result of the fact that directly depositing a separated sheet onto another sheet or onto a stack of such sheets by means of the formerly patented separating ellements is difficult to carry out accurately. Indeed, the underlying sheet or stack, is too uneven (rough surface, hairy, etc.) and often too deformable to place a new sheet thereon, so that the latter may shift, or locally be pulled out of alignment in an uncontrollable manner, or lies in wrinkles instead of flat. When depositing the tightened sheet and retracting the pricking elements, the sheet will slightly contract. Due to frictional contact with the underlying sheet, the latter, which is in untightened condition, may also undesirably contract and become wrinkled.
The invention now provides means whereby both disadvantages are simultaneously avoided by applying an improved process and apparatus for automatically and simultaneously separating sheets from several stacks and further depositing the engaged sheets in an accurate position, whereby said sheets are picked from superimposes stacks (instead of stacks placed side-by-side as formerly proposed) by means of several groups of separating elements, more particularly pick-up heads of the type described in the Belgian Pat. No. 816,940. More particularly, the invention provides means to place the picked sheets accurately one on top of the other in a suitable relative position.
Indeed, when sheets, for example size cut textiles in readymade clothing factories, are to be fed from stacks that come from the cutting tables to, for example, stitching machines for sewing on buttons and making buttonholes and hems or the like, then it is an essential requirement that the sheets arrive at the feeding mechanism in front of the stitching head in a correct position and orientation. Also when, for example, two sheets are to be automatically stitched together, both the positioning of the sheets on each other and the position and orientation of the combination of the sheet layers relative to the stitching head must be faultless in order to produce accurate and impeccable automatic stitching work.
The different superimposed tables on which stacks of sheets are placed are for that purpose in a first process brought by vertical translation into contact with the sets of pick-up devices that are properly disposed between or over them. The sheets are picked up and the tables with sheet stacks are again moved away from each other in the vertical direction to separate the engaged and tightened sheets from the immediately underlying stacks. Next, supporting means for these sheets are slid between each engaged sheet and the stack immediately underneath. The sheets are then disengaged from the sets of pick-up devices, so that they drop on the supporting means underneath and are removed horizontally from beneath the pick-up heads and possibly fed to the feeding mechanisms of the stitching machines.
When it is intended to place the separated sheets on each other, in a suitable relative position, then the removed supporting means with the sheets thereon are brought together by vertical translation, whereby at the same time these removed sheets are mutually connected in places located one above the other through suitable apertures in the supporting means. Finally the mutually connected sheets are removed from between the supporting means and supplied to the feeding mechanisms of the stitching machines or to the operator.
The improved automatic apparatus for carrying out these processes comprises a framecomposed of a number of vertical edge supports that are, among other things, mutually connected at their upper ends by suitable transverse sections. A number of pick-up heads are fixed to the underside of these uppermost transverse section. Between the vertical supporting sections, vertically movable horizontal tables are disposed, whose undersides are also provided with adapted sets of pick-up heads. At the underside of the bottommost table, pressure means are provided for moving the tables up and down. The apparatus further comprises horizontal supporting means, for example plates for the sheets separated by the pick-up heads, as well as means for inserting in a suitable manner said supporting means between the sets of pick-up heads and the immediately underlying stacks for removing the supporting means from between the pick-up heads and the stacks and for feeding them to, for example, the feeding mechanisms of stitching machines.
When the separated sheets are to be placed one on the other, the apparatus is further equipped with means for bringing together the removed supporting means with the sheets on them and for simultaneously mutually connecting the sheets in places located one above the other through suitable apertures in said supporting means. It is obvious that these joining and connecting means are so made that they permit automatic removal of the mutually connected sheets from between the supporting means and to feed them to stitching machines.